With reference to FIG. 1, ventilation of a conventional engine cooling permanent magnet DC brush motor 10 is shown. The airflow path through the motor 10 is indicated by the curved lines A. Air is drawn through the motor 10 via venting holes 12 (FIG. 2) in the end cap 14. A fan hub 16 with fins 18 (FIG. 4) creates a low pressure region at the stator end 21 such that hot air from the motor 10 is drawn out through vent holes 20 in the stator 22 (FIG. 3). Although not shown in FIG. 1, it can be appreciated that the hub 16 is mounted to the fan adaptor plate 25 and provides some splash protection to holes 20.
The conventional vented motor configuration may not fulfill muddy-water spray test requirements stipulated by some auto manufacturers. An excessive amount of mud can enter the motor through the holes 12 and can eventually form a very abrasive and poor conductive layer on the top of the commutator bars. Furthermore, solidified mud can seize the brush in the brush tube. Consequently, the applied voltage is not being conveyed to the armature winding and thus, the motor can stop operating.
In the past, when a splash shield was required, it was integrated into a plastic module. This configuration was accomplished by closing an opening on the plastic module at the motor end cap side. However, this type of configuration limited the motor mounting to a plastic shroud to front mount only. Furthermore, a larger axial space is required for such module/motor and fan assembly.
There are also a variety of different closed end cap motor configurations available on the market. However, the closed end cap motor power level is limited to low or medium power depending on the durability requirements specified by the auto manufacturers.
Thus, there is a need to provide splash coverage to venting holes of a vented end cap for a motor.